package com.fzy.leetcode.editor.cn;
//2023-03-20 20:17:38
//给定一个已排序的链表的头 head ， 删除原始链表中所有重复数字的节点，只留下不同的数字 。返回 已排序的链表 。 
//
// 
//
// 示例 1： 
// 
// 
//输入：head = [1,2,3,3,4,4,5]
//输出：[1,2,5]
// 
//
// 示例 2： 
// 
// 
//输入：head = [1,1,1,2,3]
//输出：[2,3]
// 
//
// 
//
// 提示： 
//
// 
// 链表中节点数目在范围 [0, 300] 内 
// -100 <= Node.val <= 100 
// 题目数据保证链表已经按升序 排列 
// 
//
// Related Topics 链表 双指针 👍 1079 👎 0

import java.util.List;

class RemoveDuplicatesFromSortedListIi {
    public static void main(String[] args) {
        //创建该题目的对象方便调用
        Solution solution = new RemoveDuplicatesFromSortedListIi().new Solution();
    }

    public class ListNode {
        int val;
        ListNode next;
        ListNode() {}
        ListNode(int val) { this.val = val; }
        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
    }
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode dummy = new ListNode(0);

        if(head == null){
            return null;
        }
        dummy.next = head;
        ListNode cur = head;
        ListNode pre = dummy;
        int count = 0;
        while (cur != null && cur.next != null){
            if(cur.val == cur.next.val){
                cur.next = cur.next.next;
                count++;
            }else {
                if(count>0){
                    pre.next = cur.next;
                    count = 0;
                }else {
                    pre = cur;
                }
                cur = cur.next;
            }
        }
        if(count > 0){
            pre.next = cur.next;
        }
        return dummy.next;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}